Linear estimates of disease progression predict survival in patients with amyotrophic lateral sclerosis

Identifying patterns in amyotrophic lateral sclerosis progression from sparse longitudinal data

The clinical presentation of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease, varies widely across patients, making it challenging to determine if potential therapeutics slow progression. We sought to determine whether there were common patterns of disease progression that could aid in the design and analysis of clinical trials. We developed an approach based on a mixture of Gaussian processes to identify clusters of patients sharing similar disease progression patterns, modeling their average trajectories and the variability in each cluster. We show that ALS progression is frequently nonlinear, with periods of stable disease preceded or followed by rapid decline. We also show that our approach can be extended to Alzheimer's and Parkinson's diseases. Our results advance the characterization of disease progression of ALS and provide a flexible modeling approach that can be applied to other progressive diseases.

Protocol for psychometric evaluation of the Amyotrophic Lateral Sclerosis - Bulbar Dysfunction Index (ALS-BDI): a prospective longitudinal study

INTRODUCTION

Early detection and tracking of bulbar dysfunction in amyotrophic lateral sclerosis (ALS) are critical for directing management of the disease. Current clinical bulbar assessment tools are lacking, while existing physiological instrumental assessments are often inaccessible and cost-prohibitive for clinical application. The goal of our research is to develop and validate a brief and reliable, clinician-administered assessment tool-the ALS-Bulbar Dysfunction Index (ALS-BDI). This publication describes the study protocol that has been established to ascertain the tools' psychometric properties.

METHODS AND ANALYSIS

The ALD-BDI's development closely follows guidelines outlined by the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN). Through the proposed study protocol, we expect to establish psychometric properties of both individual test items of the ALS-BDI as well as the final version of the entire tool, including test-retest and inter-rater reliability, construct validity using gold-standard assessment methods and responsiveness.

ETHICS AND DISSEMINATION

This study has been reviewed and approved by research ethics boards at two data collection sites: Sunnybrook Health Science Centre, primary (Toronto, Canada; ID3080) and Mass General Brigham (#2013P001746, Boston, USA). Prior to participation in the study, the participants sign the informed consent in accordance with the Declaration of Helsinki. Once validated, the ALS-BDI will be disseminated to key stakeholders. Following validation, the ALS-BDI and any required training material will be implemented for clinical use in a context of a multidisciplinary ALS clinic and used as an outcome measure for clinical trials in ALS research.

Safety and efficacy of bone marrow derived-mesenchymal stem cells transplantation in patients with amyotrophic lateral sclerosis

Stem cell-based treatments have emerged as potentially effective approaches to delay the progression of amyotrophic lateral sclerosis (ALS). This study was designed as a single-center, prospective, and open-label study without a placebo control group to assess the safety and efficacy of concurrent intrathecal (IT) and intravenous (IV) administration of autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) in patients with ALS. Autologous BM-MSCs were isolated and expanded under standard conditions. Fifteen patients were neurologically examined before BM-MSCs transplantation (1 × 10 ⁶ cells/kg BW) to evaluate the rate of pre-treatment disease progression. To assess the safety and efficacy, patients were examined at 1, 3, and 6 months following the treatment with BM-MSCs. Adverse reactions were assessed, and the clinical outcome was determined by the evaluation of the ALS functional rating scale-revised (ALSFRS-R) and forced vital capacity (FVC). No serious adverse reaction was observed after combined IT and IV administration of BM-MSCs. The mean ALSFRS-R and FVC values remained stable during the first 3 months of the treatment. However, a significant reduction in ALSFRS-R and FVC levels was observed in these patients 6 months after BM-MSCs administration. Our study revealed that the concurrent IT and IV application of BM-MSCs in patients with ALS is a safe procedure. Furthermore, our data indicate a temporary delay in the progression of ALS after a single combined IT and IV administration of BM-MSCs. Further studies are required to explore if the repeated applications of BM-MSCs could prolong survival and delay the progression of ALS.

Pattern of lung function decline in patients with amyotrophic lateral sclerosis: implications for timing of noninvasive ventilation

BACKGROUND

The course of lung function decline in amyotrophic lateral sclerosis (ALS) and the effect of noninvasive positive-pressure ventilation (NIPPV) on that decline are uncertain. We sought to model lung function decline, determine when NIPPV is initiated along that course, and assess its impact on the course of decline.

METHODS

An observed sigmoid pattern of forced vital capacity decline was reproduced with a four-parameter nonlinear mixed-effects logistic model.

RESULTS

Analyses were performed on 507 patients overall and in 353 patients for whom a determination of adherence to NIPPV was ascertained. A sigmoid bi-asymptotic model provided a statistical fit of the data and showed a period of stable vital capacity, followed by an accelerated decline, an inflection point, then a slowing in decline to a plateau. By the time NIPPV was initiated in accordance with reimbursement guidelines, vital capacity had declined by ≥85% of the total range. Nearly half of the total loss of vital capacity occurred over 6.2 months centred at an inflection point occurring 17 months after disease onset and 5.2 months before initiation of NIPPV at a vital capacity of about 60%. Fewer bulbar symptoms and a faster rate of decline of lung function predicted adherence to NIPPV, but the intervention had no impact on final vital capacity.

CONCLUSIONS

In patients with ALS, vital capacity decline is rapid but slows after an inflection point regardless of NIPPV. Initiating NIPPV along reimbursement guidelines occurs after ≥85% of vital capacity loss has already occurred.

Results from Phase I Clinical Trial with Intraspinal Injection of Neural Stem Cells in Amyotrophic Lateral Sclerosis: A Long-Term Outcome

The main objective of this phase I trial was to assess the feasibility and safety of microtransplanting human neural stem cell (hNSC) lines into the spinal cord of patients with amyotrophic lateral sclerosis (ALS). Eighteen patients with a definite diagnosis of ALS received microinjections of hNSCs into the gray matter tracts of the lumbar or cervical spinal cord. Patients were monitored before and after transplantation by clinical, psychological, neuroradiological, and neurophysiological assessment. For up to 60 months after surgery, none of the patients manifested severe adverse effects or increased disease progression because of the treatment. Eleven patients died, and two underwent tracheotomy as a result of the natural history of the disease. We detected a transitory decrease in progression of ALS Functional Rating Scale Revised, starting within the first month after surgery and up to 4 months after transplantation. Our results show that transplantation of hNSC is a safe procedure that causes no major deleterious effects over the short or long term. This study is the first example of medical transplantation of a highly standardized cell drug product, which can be reproducibly and stably expanded ex vivo, comprising hNSC that are not immortalized, and are derived from the forebrain of the same two donors throughout this entire study as well as across future trials. Our experimental design provides benefits in terms of enhancing both intra‐ and interstudy reproducibility and homogeneity. Given the potential therapeutic effects of the hNSCs, our observations support undertaking future phase II clinical studies in which increased cell dosages are studied in larger cohorts of patients. stem cells translational medicine2019;8:887&897

Using an Anchor to Improve Linear Predictions with Application to Predicting Disease Progression

Linear models are some of the most straightforward and commonly used modelling approaches. Consider modelling approximately monotonic response data arising from a time-related process. If one has knowledge as to when the process began or ended, then one may be able to leverage additional assumed data to reduce prediction error. This assumed data, referred to as the "anchor," is treated as an additional data-point generated at either the beginning or end of the process. The response value of the anchor is equal to an intelligently selected value of the response (such as the upper bound, lower bound, or 99^th percentile of the response, as appropriate). The anchor reduces the variance of prediction at the cost of a possible increase in prediction bias, resulting in a potentially reduced overall mean-square prediction error. This can be extremely effective when few individual data-points are available, allowing one to make linear predictions using as little as a single observed data-point. We develop the mathematics showing the conditions under which an anchor can improve predictions, and also demonstrate using this approach to reduce prediction error when modelling the disease progression of patients with amyotrophic lateral sclerosis.

Using automated electronic medical record data extraction to model ALS survival and progression

BACKGROUND

To assess the feasibility of using automated capture of Electronic Medical Record (EMR) data to build predictive models for amyotrophic lateral sclerosis (ALS) outcomes.

METHODS

We used an Informatics for Integrating Biology and the Bedside search discovery tool to identify and extract data from 354 ALS patients from the University of Kansas Medical Center EMR. The completeness and integrity of the data extraction were verified by manual chart review. A linear mixed model was used to model disease progression. Cox proportional hazards models were used to investigate the effects of BMI, gender, and age on survival.

RESULTS

Data extracted from the EMR was sufficient to create simple models of disease progression and survival. Several key variables of interest were unavailable without including a manual chart review. The average ALS Functional Rating Scale - Revised (ALSFRS-R) baseline score at first clinical visit was 34.08, and average decline was - 0.64 per month. Median survival was 27 months after first visit. Higher baseline ALSFRS-R score and BMI were associated with improved survival, higher baseline age was associated with decreased survival.

CONCLUSIONS

This study serves to show that EMR-captured data can be extracted and used to track outcomes in an ALS clinic setting, potentially important for post-marketing research of new drugs, or as historical controls for future studies. However, as automated EMR-based data extraction becomes more widely used there will be a need to standardize ALS data elements and clinical forms for data capture so data can be pooled across academic centers.

Using an onset-anchored Bayesian hierarchical model to improve predictions for amyotrophic lateral sclerosis disease progression

BACKGROUND

Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's disease, is a rare disease with extreme between-subject variability, especially with respect to rate of disease progression. This makes modelling a subject's disease progression, which is measured by the ALS Functional Rating Scale (ALSFRS), very difficult. Consider the problem of predicting a subject's ALSFRS score at 9 or 12 months after a given time-point.

METHODS

We obtained ALS subject data from the Pooled Resource Open-Access ALS Clinical Trials Database, a collection of data from various ALS clinical trials. Due to the typical linearity of the ALSFRS, we consider several Bayesian hierarchical linear models. These include a mixture model (to account for the two potential classes of "fast" and "slow" ALS progressors) as well as an onset-anchored model, in which an additional artificial data-point, using time of disease onset, is utilized to improve predictive performance.

RESULTS

The onset-anchored model had a drastically reduced posterior predictive mean-square-error distributions, when compared to the Bayesian hierarchical linear model or the mixture model under a cross-validation approach. No covariates, other than time of disease onset, consistently improved predictive performance in either the Bayesian hierarchical linear model or the onset-anchored model.

CONCLUSIONS

Augmenting patient data with an additional artificial data-point, or onset anchor, can drastically improve predictive modelling in ALS by reducing the variability of estimated parameters at the cost of a slight increase in bias. This onset-anchored model is extremely useful if predictions are desired directly after a single baseline measure (such as at the first day of a clinical trial), a feat that would be very difficult without the onset-anchor. This approach could be useful in modelling other diseases that have bounded progression scales (e.g. Parkinson's disease, Huntington's disease, or inclusion-body myositis). It is our hope that this model can be used by clinicians and statisticians to improve the efficacy of clinical trials and aid in finding treatments for ALS.

The ALSFRS as an outcome measure in therapeutic trials and its relationship to symptom onset

The reduction in ALS Functional Rating Score (ALSFRS) from reported symptom onset to diagnosis is used to estimate rate of disease progression. ALSFRS decline may be non-linear or distorted by drop-outs in therapeutic trials, reducing the reliability of change in slope as an outcome measure. The PRO-ACT database uniquely allows such measures to be explored using historical data from negative therapeutic trials. The decline of functional scores was analysed in 18 pooled trials, comparing rates of decline based on symptom onset with rates calculated between interval assessments. Strategies to mitigate the effects of trial drop-out were considered. Results showed that progression rate calculated by symptom onset underestimated the subsequent rate of disability accumulation, although it predicted survival more accurately than four-month interval estimates of δALSFRS or δFVC. Individual ALSFRS and FVC progression within a typical trial duration were linear. No simple solution to correct for trial drop-out was identified, but imputation using δALSFRS appeared least disruptive. In conclusion, there is a trade-off between the drive to recruit trial participants soon after symptom onset, and reduced reliability of the ALSFRS-derived progression rate at enrolment. The need for objective markers of disease activity as an alternative to survival-based end-points is clear and pressing.

Electrically evoked multiplet discharges are associated with more marked clinical deterioration in motor neuron disease

INTRODUCTION

The aim of this study was to determine whether electrically evoked multiplet discharges (MDs) are related to severity of clinical deterioration in motor neuron disease (MND).

METHODS

Stimulated high-density surface electromyographic (HDsEMG) recordings were performed in thenar muscles. Data were collected from 31 MND patients. MDs from the HDsEMG recordings were determined at baseline. ALSFRS-R scores were obtained at baseline and at a maximum of 16 weeks follow-up.

RESULTS

The presence of MDs was associated with progressive deterioration of ALSFRS-R score (P = 0.02) and fine motor function (FMF) (P < 0.001). Patients who had a higher number of motor units that generated MDs (r = 0.61, P < 0.001) and patients who had a higher number of MDs (as percentage of applied stimuli) (r = 0.59, P = 0.001) had a more severe decline in FMF.

CONCLUSIONS

Electrically evoked MDs are associated with more marked clinical deterioration in patients with MND.

Prognostic models based on patient snapshots and time windows: Predicting disease progression to assisted ventilation in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a devastating disease and the most common neurodegenerative disorder of young adults. ALS patients present a rapidly progressive motor weakness. This usually leads to death in a few years by respiratory failure. The correct prediction of respiratory insufficiency is thus key for patient management. In this context, we propose an innovative approach for prognostic prediction based on patient snapshots and time windows. We first cluster temporally-related tests to obtain snapshots of the patient's condition at a given time (patient snapshots). Then we use the snapshots to predict the probability of an ALS patient to require assisted ventilation after k days from the time of clinical evaluation (time window). This probability is based on the patient's current condition, evaluated using clinical features, including functional impairment assessments and a complete set of respiratory tests. The prognostic models include three temporal windows allowing to perform short, medium and long term prognosis regarding progression to assisted ventilation. Experimental results show an area under the receiver operating characteristics curve (AUC) in the test set of approximately 79% for time windows of 90, 180 and 365 days. Creating patient snapshots using hierarchical clustering with constraints outperforms the state of the art, and the proposed prognostic model becomes the first non population-based approach for prognostic prediction in ALS. The results are promising and should enhance the current clinical practice, largely supported by non-standardized tests and clinicians' experience.

Neuropsychological investigation in Chinese patients with progressive muscular atrophy

Background

Progressive muscular atrophy (PMA) is a rare type of degenerative motor neuron disease (MND) of which the onset happens in adult period. Despite its well-defined clinical characteristics, its neuropsychological profile has remained poorly understood, considering the consensus of cognitive and behavioral impairment reached in amyotrophic lateral sclerosis (ALS).

Methods

We conducted a cross-sectional evaluation of Chinese PMA patients with a series of comprehensive batteries emphasizing the executive and attention function, and covering other domains of memory, language, visuospatial function, calculation and behavior as well. Their performances were compared with those of age- and education-matched ALS and healthy controls (HC).

Results

21 patients newly diagnosed with PMA were consecutively enrolled into our ALS and other MND registry platform, accounting for 14.7% of all the incident MND cases registered during the same period. 20 patients who completed the neuropsychological batteries were included into analysis. Compared with HC, PMA performed significantly worse in maintenance function of attention, while they exhibited quantitative similarity to ALS in all behavioral inventories and neuropsychological tests except the time for Stroop interference effect.

Conclusion

PMA could display mild cognitive dysfunction in the same frontal-mediated territory of ALS but in a lesser degree, whereas they did not differ from ALS behaviorally.

Challenges in the Understanding and Treatment of Amyotrophic Lateral Sclerosis/Motor Neuron Disease

With the acceleration in our understanding of ALS and the related motor neuron disease has come even greater challenges in reconciling all of the proposed pathogenic mechanisms and how this will translate into impactful treatments. Fundamental issues such as diagnostic definition(s) of the disease spectrum, relevant biomarkers, the impact of multiple novel genetic mutations and the significant effect of symptomatic treatments on disease progression are all areas of active investigation. In this review, we will focus on these key issues and highlight the challenges that confront both clinicians and basic science researchers.

[Epidemiology, clinical spectrum of ALS and differential diagnoses]

Amyotrophic Lateral Sclerosis (ALS) is the most common motor neuron disease in adults. Its incidence in France is estimated at 2.5 per 100,000 population and its prevalence between 5 and 8 per 100,000 inhabitants. Good prognostic factors are age of early onset, a longer time to diagnosis, initial damage to the spinal onset, early management of undernutrition and restrictive respiratory failure. The diagnosis of ALS is primarily clinical and is based on the evidence of involvement of the central motor neuron and peripheral neuron (NMP) in different territories or spinal or bulbar. The EMG confirms the achievement of NMP, shows the extension to clinically preserved areas and allows to exclude some differential diagnoses. The clinical spectrum of ALS is broad: conventional forms beginning brachial, lower limb or bulbar onsets, rarer forms to start breathing, pyramidal forms, forms with cognitive and behavioural impairment. In 5-10% of cases, ALS is familial. In 15% of cases, it is associated with frontotemporal degeneration rather than orbito-frontal type. The main differential diagnoses are guided by the clinic: combining pure motor neuropathy with or without conduction block, post-polio syndrome, cramp-fasciculation syndrome, myasthenia gravis, paraneoplastic syndromes, Sjögren syndrome, retroviral infections, some endocrine disorders, some metabolic diseases, genetic diseases (Kennedy and SMA) and inclusion body myositis.

Neck weakness is a potent prognostic factor in sporadic amyotrophic lateral sclerosis patients

OBJECTIVE

To clarify the emergence of muscle weakness in regions of the body that affect survival, and deterioration in activities of daily living (ADL) in amyotrophic lateral sclerosis (ALS) patients.

METHODS

We conducted a multicentre-based prospective cohort study of patients with ALS. We enrolled 401 sporadic patients with ALS. Death or the introduction of invasive ventilation was defined as the primary endpoint, and the time to five clinical markers of ADL deterioration associated with bulbar paralysis or limb weakness were defined as ADL milestones. Muscle weakness was assessed in the neck flexor muscles; the bilateral abductors of the shoulders; the bilateral wrist extensor muscles; the bilateral flexor muscles of the hips; and the bilateral ankle dorsiflexion muscles. We performed Cox proportional hazards regression analyses for the primary endpoint and the five ADL milestones, adjusting for known covariate prognostic factors for ALS.

RESULTS

The Medical Research Council (MRC) score for the neck flexors was the most significant prognostic factor for the primary endpoint (HR 0.74, p<0.001), loss of speech (HR 0.66, p<0.001), and loss of swallowing function (HR 0.73, p<0.001), and was one of the significant prognostic factors for loss of upper limb function, difficulty turning in bed, and loss of walking ability (p=0.001, 0.002, and 0.008, respectively). The MRC score for the neck flexors was also a significant prognostic factor for covariates of the previously reported prognostic factors.

CONCLUSIONS

Neck weakness is an independent prognostic factor for survival and deterioration in ADL in Patients with ALS.

Rates of progression of weight and forced vital capacity as relevant measurement to adapt amyotrophic lateral sclerosis management for patient Result of a French multicentre cohort survey

OBJECTIVES

To compare survival, to describe the progression of anthropometry, pulmonary capacity and functioning in ALS (Amyotrophic Lateral Sclerosis) and to identify the most relevant variables to adapt ALS management for patients.

METHODS

A cohort study was performed in French ALS centres between January 2003 and July 2005. Eligible patients were treated by Riluzole and had a slow vital capacity (SVC) or a forced vital capacity (FVC) at least equal to 60%. Demographic, medical and ALS characteristics were registered. Manual Muscular Testing (MMT) and ALS Functional Rating Scale (ALSFRS) were performed. Kaplan Meier method was used to analyse survival. ALS progression was measured by the percentage weight, FVC, SVC, MMT and ALSFRS loss and was analysed as longitudinal data using mixed model.

RESULTS

Three hundred and eighty three patients were included. The median survival since ALS diagnosis was 2.34 years (95%CI 2.10-2.65). Mixed model analyses revealed a more significant worsening progression of weight and FVC loss for bulbar onset. The drop of ALSFRS and SVC is similar whatever the ALS forms.

CONCLUSIONS

Rates of progression of weight and FVC should be regularly watched over to support neurologists to adapt ALS management for patients.

Prognostic categories for amyotrophic lateral sclerosis

Our objective was to generate a prognostic classification method for amyotrophic lateral sclerosis (ALS) from a prognostic model built using clinical variables from a population register. We carried out a retrospective multivariate analysis of 713 patients with ALS over a 20-year period from the South-East England Amyotrophic Lateral Sclerosis (SEALS) population register. Patients were randomly allocated to 'discovery' or 'test' cohorts. A prognostic score was calculated using the discovery cohort and then used to predict survival in the test cohort. The score was used as a predictor variable to split the test cohort in four prognostic categories (good, moderate, average, poor). The accuracy of the score in predicting survival was tested by checking whether the predicted survival fell within the actual survival tertile which that patient was in. A prognostic score generated from one cohort of patients predicted survival for a second cohort of patients (r(2) = 0.72). Six variables were included in the survival model: age at onset, diagnostic delay, El Escorial category, use of riluzole, gender and site of onset. Cox regression demonstrated a strong relationship between these variables and survival (χ(2) 80.8, df 1, p < 0.0001, n = 343) in the test cohort. Kaplan-Meier analysis demonstrated a significant difference in survival between clinical categories (log rank 161.932, df 3, p < 0.001), and the prognostic score generated for the test cohort accurately predicted survival in 64% of the patients. In conclusion, it is possible to correctly classify patients into prognostic categories using clinical data easily available at time of diagnosis.

Repeated courses of granulocyte colony-stimulating factor in amyotrophic lateral sclerosis: clinical and biological results from a prospective multicenter study

Granulocyte colony-stimulating factor (G-CSF) induces a transient mobilization of hematopoietic progenitor cells from bone marrow to peripheral blood. Our aim was to evaluate safety of repeated courses of G-CSF in patients with amyotrophic lateral sclerosis (ALS), assessing disease progression and changes in chemokine and cytokine levels in serum and cerebrospinal fluid (CSF). Twenty-four ALS patients entered an open-label, multicenter trial in which four courses of G-CSF and mannitol were administered at 3-month intervals. Levels of G-CSF were increased after treatment in the serum and CSF. Few and transitory adverse events were observed. No significant reduction of the mean monthly decrease in ALSFRS-R score and forced vital capacity was observed. A significant reduction in CSF levels of monocyte chemoattractant protein-1 (MCP-1) and interleukin-17 (IL-17) was observed. G-CSF treatment was safe and feasible in a multicenter series of ALS patients. A decrease in the CSF levels of proinflammatory cytokines MCP-1 and IL-17 was found, indicating a G-CSF-induced central anti-inflammatory response.

Use of respiratory function tests to predict survival in amyotrophic lateral sclerosis

Respiratory function tests (RFTs) are commonly used as a measure of progression in ALS. This study assessed the ability of various RFTs to predict survival in ALS patients. Subjects with ALS had one or more measurements of seated and supine FVC, maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). Kaplan-Meier (KM) analysis was used to determine whether patients with abnormal RFTs had shorter survival than those with normal RFTs. The sensitivity and specificity of RFTs as predictors of two-year survival were calculated from receiver operating characteristic (ROC) curves. With KM analysis, subjects with abnormal values of seated FVC, supine FVC, MIP and MEP had significantly reduced survival compared to subjects with normal values. With ROC curves, a normal supine FVC was highly predictive for two-year survival and had superior sensitivity over seated FVC. Slower rates of decline in seated or supine FVC were strong predictors of two-year survival. Our study demonstrates that respiratory function measurements are useful to predict survival in ALS patients. We show that measurements of FVC in the supine position are worth including in the assessment of respiratory function in ALS.

Progression in ALS is not linear but is curvilinear

The aim of the study is to determine the shape of the progression curve in ALS, assess the impact of clinical variables on the rate of progression, and evaluate the association between functional decline and survival. Data were prospectively collected and entered into a clinical database from all patients seen in 2002-2008 at the Centre SLA, Hôpital de la Salpêtrière, Paris. Variables analyzed were demographic and baseline information, the ALS functional rating scale (ALSFRS-R), strength testing (MMT), and survival. Generalized additive mixed models characterized changes in ALSFRS-R and MMT scores over time. Linear mixed effects assessed the impact of demographic and clinical measures on rate of progression and Cox models examined their effect on survival. Of 2,452 patients with ALS identified, 1,884 had adequate data for analysis. The ALSFRS-R and MMT declined in a curvilinear way; a quadratic fit described the trends but a linear fit did not. The total ALSFRS-R score was negatively associated with age-of-onset (p < 0.001), and positively associated with baseline ALSFRS-R (p < 0.001) as well as more severe bulbar features (p < 0.001). Higher rate of decline in ALSFRS-R and MMT, older age-at-onset and bulbar-onset predicted shorter survival. Deterioration in ALS is non-linear. The early and late phases of the illness show the most rapid rates of decline. Older age and bulbar signs are associated with a steeper decline, and along with more rapid initial rate of decline, but not current functional status, also predict survival.

Prognostic factors in ALS: A critical review

We have performed a systematic review to summarize current knowledge concerning factors related to survival in ALS and to evaluate the implications of these data for clinical trials design. The median survival time from onset to death ranges from 20 to 48 months, but 10-20% of ALS patients have a survival longer than 10 years. Older age and bulbar onset are consistently reported to have a worse outcome. There are conflicting data on gender, diagnostic delay and El Escorial criteria. The rate of symptom progression was revealed to be an independent prognostic factor. Psychosocial factors, FTD, nutritional status, and respiratory function are also related to ALS outcome. The effect of enteral nutrition on survival is still unclear, while NIPPV has been found to improve survival. There are no well established biological markers of progression, although some are likely to emerge in the near future. These findings have relevant implications for the design of future trials. Randomization, besides the type of onset, should take into account age, respiratory status at entry, and a measure of disease progression pre-entry. Alternative trial designs can include the use of natural history controls, the so-called minimization method for treatment allocation, and the futility approach.

ALS motor phenotype heterogeneity, focality, and spread: deconstructing motor neuron degeneration

Heterogeneity of motor phenotypes is a clinically well-recognized fundamental aspect of amyotrophic lateral sclerosis (ALS) and is determined by variability of 3 independent primary attributes: body region of onset; relative mix of upper motor neuron (UMN) and lower motor neuron (LMN) deficits; and rate of progression. Motor phenotypes are determined by the anatomy of the underlying neuropathology and the common defining elements underlying their heterogeneity are that motor neuron degeneration is fundamentally a focal process and that it spreads contiguously through the 3-dimensional anatomy of the UMN and LMN levels, thus causing seemingly complex and varied clinical manifestations. This suggests motor neuron degeneration in ALS is in actuality a very orderly and actively propagating process and that fundamental molecular mechanisms may be uniform and their chief properties deduced. This also suggests opportunities for translational research to seek pathobiology directly in the less affected regions of the nervous system.

Amyotrophic lateral sclerosis: Prognostic indicators of survival

Amyotrophic lateral sclerosis (ALS) has a fatal outcome in about three years, but survival is known to vary considerably, making it difficult to predict disease duration in individual cases. The aim of this study was to investigate possible early prognostic factors of ALS survival. We included 123 probable or definite cases of ALS, with disease onset between 1989 and 1998, and with a follow-up of at least one year. Survival functions were obtained using both the Kaplan-Meier and the actuarial methods. Subgroups, formed on the basis of gender, area of residence, work, and age at and site of onset, were compared using the logrank test and Cox's proportional hazards method (survival functions), and applying the Grizzle, Starmer, Koch (1969), and Koch, Johnson, Tolley (1972) methods (one-year survival probability trends). The survival curves dipped sharply in the first three years, followed by a flattening trend, with 50% of patients dying within 2.5 years, and 89% over seven years. The clinical form with lower limb onset was associated with longer survival than the upper limb onset and bulbar forms (median survival: 39, 27, and 25 months, respectively). Survival was also affected by age at onset (median survival: 34, 27, and 23 months for onset <60, 60-75, and >75 years, respectively), area of residence (median survival: 24 months in mountainous areas, 32 elsewhere), and type of work (median survival: 25 months in agricultural workers, 33.5 in others). Gender did not influence survival, whereas percutaneous endoscopic gastrostomy placement and invasive ventilation did. The estimation of individual ALS survival is important to allow the patient to plan for his future and to make optimal use of medical and community resources. Although age at and site of onset, area of residence, and agricultural work were found to influence survival, there remains an unexplained heterogeneous progression of the disease, suggesting the influence of other, as yet unknown, prognostic factors. The identification of a definite set of prognostic factors may allow physicians to make more reliable survival predictions at diagnosis.

Analysis of factors that modify susceptibility and rate of progression in amyotrophic lateral sclerosis (ALS)

We conducted case-control and prospective longitudinal studies to examine risk factors and predictors of disease progression for ALS. Ninety-five subjects with ALS and 106 healthy control subjects were enrolled. All subjects completed a risk factor questionnaire at enrollment. The ALS subjects were prospectively followed for one year to define factors that influence the rate of disease progression, measured by rate of change in percent predicted forced vital capacity (%FVC) and the ALS functional rating scale (ALSFRS) score. The association of each potential risk factor with ALS was determined using univariate logistic regression. A random slope model was used to determine the association of each risk factor with disease progression. The demographic characteristics of ALS subjects and controls at enrollment did not differ. Significant risk factors for ALS included reported exposure to lead (p = 0.02) and pesticides (p = 0.03). Disease progression was faster in the ALS subjects having bulbar onset and a shorter time period between onset of symptoms and diagnosis. Pertinent variables not associated with either causation or progression of ALS included physical activity, cigarette smoking and a history of physical trauma or other clinical disorders.

Prognostic factors for survival in amyotrophic lateral sclerosis patients treated with riluzole

The objective of this study was to identify prognostic factors for survival in amyotrophic lateral sclerosis from a large prospective observational study performed in France. The study included a cohort of 2069 patients fulfilling broad entry criteria treated with riluzole. Over 100 demographic, biological, clinical and quality-of-life variables were monitored and assessed for their effect on survival. Patients were randomized post hoc into two groups: one group (two-thirds of the patients) to generate the prognostic models and one group (one-third of the patients) to validate the resulting models. Thirteen variables were found to affect survival independently and were used to construct a survival prediction score, RL401. These included age, disease duration, slow vital capacity, intensity of tiredness (visual analogue scale), number of body levels with spasticity, atrophy and/or fasciculations, cough, distal muscle strength, household income, depression and two biological parameters, plasma creatinine levels and neutrophil counts. A simplified score, RL401S, was constructed, designed to be easy to use and interpret. The predictive powers of the two scores were similar.

Bias in Markov models of disease

We examine bias in Markov models of diseases, including both chronic and infectious diseases. We consider two common types of Markov disease models: ones where disease progression changes by severity of disease, and ones where progression of disease changes in time or by age. We find sufficient conditions for bias to exist in models with aggregated transition probabilities when compared to models with state/time dependent transition probabilities. We also find that when aggregating data to compute transition probabilities, bias increases with the degree of data aggregation. We illustrate by examining bias in Markov models of Hepatitis C, Alzheimer's disease, and lung cancer using medical data and find that the bias is significant depending on the method used to aggregate the data. A key implication is that by not incorporating state/time dependent transition probabilities, studies that use Markov models of diseases may be significantly overestimating or underestimating disease progression. This could potentially result in incorrect recommendations from cost-effectiveness studies and incorrect disease burden forecasts.

Causes of death amongst French patients with amyotrophic lateral sclerosis: a prospective study

BACKGROUND AND PURPOSE

To prospectively investigate causes of death and the circumstances surrounding death in 302 patients with amyotrophic lateral sclerosis (ALS). The functional status of patients immediately before death was also determined.

METHODS

Information was obtained from neurologists at ALS centres, patients' files, and, when deaths occurred outside a medical facility, attending physicians.

RESULTS

Most patients (63%) died in a medical facility. The most frequently reported cause of death was respiratory failure (77%), including terminal respiratory insufficiency (58%), pneumonia (14%), asphyxia due to a foreign body (3%) and pulmonary embolism (2%). Ten per cent of patients died from other causes: post-surgical or traumatic conditions (5%), cardiac causes (3.4%), suicide (1.3%) and sudden death of unknown origin (0.7%). The cause of death could not be determined in 13% of cases (6% inside a medical facility and 25% outside). At the time of death, only 55% of patients were receiving riluzole, 33% were undergoing non-invasive ventilation, 3% had a tracheotomy and 37% a gastrostomy.

CONCLUSION

The information provided by this study helps to improve our understanding of the natural history of the disease and may help optimize the quality of care we can offer patients at the end of life.

Disease progression and survival in ALS: first multi-state model approach

Although several prognostic factors have been identified in ALS, there remains some discordance concerning the prognostic significance of the age and clinical form at onset. In order to clarify these findings, we have analysed already known prognostic factors using a multi-state model. Two hundred and twenty-two sporadic ALS patients were followed. A simple unidirectional three-states model was used to summarize clinical course of ALS. States 1 and 2 reflected the progression of neurological impairment and state 3 represented the end of follow-up (tracheotomy or death). Gender, diagnostic delay, body mass index (BMI) and slow vital capacity (SVC) were also recorded. A time-inhomogeneous Markov model with piecewise constant transition intensities was used to estimate the effect of the covariates in each transition. The bulbar form at onset was only correlated with a more rapid clinical progression between state 1 and state 2. In contrast, an advanced age at diagnosis affected only survival from state 2. This methodological approach suggests that these two factors have a different prognostic significance: age at onset is related to patient's survival and the clinical form at onset predicts the progression of motoneuronal impairment in different regions.

Respiratory systems abnormalities and clinical milestones for patients with amyotrophic lateral sclerosis with emphasis upon survival

Respiratory system complications and abnormalities are common in patients with amyotrophic lateral sclerosis (ALS) and respiratory failure remains the most common cause of death. Extensive epidemiological longitudinal data have documented the extent, magnitude, and clinical course of these abnormalities, but few studies have provided objective information that can have prognostic significance for individual patients. In this study, the reported data represent results from a retrospective review of the medical records of 153 patients with ALS cared for at a single institution (The Penn State Milton S. Hershey Medical Center) over a 50-month period. Medical information in relation to respiratory system abnormalities and complications including pulmonary function measurements was extracted for data analyses. The intent of this review of longitudinal data from a relatively large cohort of patients with ALS was to identify clinically relevant easily-identifiable objective information and clinical milestones that could have potential prognostic significance when applied to individual patients. Demographic data including gender, survival outcome, respiratory symptoms, age of disease onset, and age at death were similar to previously published epidemiological studies: mean age at ALS disease onset was 58.9+/-12.7 years, and mean age at death was 66.7+/-10.8 years. For 151 patients with available data, the incidence of study defined respiratory complications included infectious pneumonia 13 (9%), venothromboembolism 9 (6%), and tracheostomy and mechanical ventilation 6 (4%). For 139 patients with serial measurements of forced vital capacity (FVC), median values for calculated rate of decline in FVC was 97 ml/30 days (2.4% predicted/30 days); 25% of patients had FVC rates of decline less than 52 ml/30 days (1.4% predicted/30 days) and 25% had rates of decline greater than 170 ml/30 days (4.4% predicted/30 days). Stratifying patients into two distinct clinical subgroups based upon rates of decline in FVC less than or greater than the median value of 97 ml/30 days identified an apparent two-fold increase in survival duration for ALS patients with slower rates of pulmonary physiology deterioration when referenced to either date of dyspnea onset or time from bi-level positive airway pressure (BiPAP) initiation (2.0+/-1.4 vs. 1.0+/-0.8 years; 1.9+/-1.5 vs. 1.0+/-0.9 years, respectively). We concluded that the correlation between clinically defined milestones, most importantly onset of dyspnea, and the calculated rate of decline in FVC represent obtainable and objective measurements that predict the natural course of respiratory muscle dysfunction in patients with ALS and provide important prognostic information in relation to individual patient survival duration.

Predictability of disease progression in amyotrophic lateral sclerosis

The aim of this study was to determine the predictors of disease progression in a group of 832 patients with the diagnosis of definite or probable amyotrophic lateral sclerosis (ALS). Disease progression was defined as the time to 20-point change in Appel ALS (AALS) score. The effects of individual prognostic factors on disease progression were assessed with the Kaplan-Meier life-table method. In addition, the prognostic value of each factor was estimated using both univariate and multivariate Cox proportional hazard analyses. The median time to a 20-point change in AALS score in our patient population was 9 months. Age, site of symptom onset, time between first symptom and first examination, total AALS score at first examination, and AALS preslope (rate of disease progression between first symptom and first examination) were significant and independent covariates of disease progression in our population. Identification of predictors of disease progression will facilitate better design of therapeutic trials, permitting the use of disease progression as a primary endpoint and improving baseline stratification of patient populations.

Revised statistical motor unit number estimation in the Celecoxib/ALS trial

Techniques to estimate motor unit number (MUNE) measure the number of functioning motor units in a muscle. As amyotrophic lateral sclerosis (ALS) is characterized by progressive motor unit loss, this disease offers an ideal setting for the use of MUNE. Statistical MUNE was employed in a recent multicenter trial of creatine in ALS, and was shown to be reliable, reproducible, and to decline with disease progression. However, motor unit amplitude stayed constant over 7 months, a finding believed to reflect an artifact of the method. The statistical method was revised to reflect more accurately the presence of larger motor units and employed in a 12-month study of Celecoxib in ALS. MUNE declined by 49% in 12 months; however, motor unit amplitude again stayed constant over the same period. Statistical MUNE estimates motor unit number based on the variability of response to a repeated stimulus of constant strength, with an underlying assumption that this variability is due solely to the number of motor units responding in an intermittent manner. Based on studies showing that single motor units in ALS display excessive amplitude variability when stimulated repeatedly, we show that response variability in ALS patients is in large part due to single unit changes. Thus, we conclude that the statistical method is not an appropriate measure of motor unit number in any disease associated with motor unit instability.

Motor unit number estimation predicts disease onset and survival in a transgenic mouse model of amyotrophic lateral sclerosis

Motor unit number estimation (MUNE) has proved useful in predicting rate of progression and survival in patients with amyotrophic lateral sclerosis (ALS). In animal models, it has demonstrated physiological effects of experimental medications that were not evident behaviorally. We sought to determine more specifically what aspects of function and survival that MUNE could predict in the G93A transgenic mouse model of ALS. Transgenic mice were examined in two distinct treatment studies, neither of which showed an effect of drug on survival, behavioral measures, or MUNE. MUNE was performed using a modification of the incremental stimulation method by stimulating the sciatic nerve at the sciatic notch, and recording with a circumferential surface electrode around the ipsilateral distal hindlimb. Both limbs were studied and the results averaged. MUNE was performed longitudinally on all animals from near onset to premorbid state. Each study was evaluated separately. For both studies, MUNE at initial study correlated significantly with behavioral determination of disease onset, and MUNE slope from initial to final study correlated significantly with disease duration, as measured from onset to time of death. However, the final MUNE value did not correlate with survival. Thus, in two studies involving animals with quite different disease courses, initial MUNE effectively predicted symptom onset and MUNE slope predicted survival. This suggests that MUNE has potential efficacy as a useful functional outcome measure in both animal and human studies of ALS.

Amyotrophic lateral sclerosis: early predictors of prolonged survival

OBJECTIVE

In order to define the predictors of prolonged survival available at the time of first examination we performed a historical cohort study of amyotrophis sclerosis (ALS) patients referred to our ALS Clinic over the last 20 years.

METHODS

In a group of 1034 patients with the diagnosis of definite or probable ALS the effects of individual prognostic factors on tracheostomy-free survival were assessed with the Kaplan-Meier life-table method. The prognostic value of each factor was estimated using univariate and multivariate Cox proportional hazard analyses.

RESULTS

The median survival time was 3.45 years, (95%CI 3.27-3.74). Both the univariate and multivariate Cox models indicated that younger age, limb site of onset, longer diagnostic delay, lower Appel ALS score (AALSS) at first examination, lower AALSS-rate of change between first symptom and first exam (preslope), and higher baseline forced vital capacity (FVC) were associated with longer survival. In addition, four factors: age, diagnostic delay, baseline FVC and AALSS preslope have been identified as independent predictors of survival in our patient population.

CONCLUSIONS

The identification of younger age, limb site of onset and longer diagnostic delay as predictors of prolonged survival in ALS clinic population supports the findings of several, earlier studies that were based on smaller groups of patients. More significantly, several additional variables assessed at the first examination predict longer survival: lower baseline AALSS, lower AALSS- preslope and higher baseline FVC. All of these parameters are of value in patient management and in clinical trial development.

Effects of non-invasive ventilation on survival and quality of life in patients with amyotrophic lateral sclerosis: a randomised controlled trial

BACKGROUND

Few patients with amyotrophic lateral sclerosis currently receive non-invasive ventilation (NIV), reflecting clinical uncertainty about the role of this intervention. We aimed to assess the effect of NIV on quality of life and survival in amyotrophic lateral sclerosis in a randomised controlled trial.

METHODS

92 of 102 eligible patients participated. They were assessed every 2 months and randomly assigned to NIV (n=22) or standard care (n=19) when they developed either orthopnoea with maximum inspiratory pressure less than 60% of that predicted or symptomatic hypercapnia. Primary validated quality-of-life outcome measures were the short form 36 mental component summary (MCS) and the sleep apnoea quality-of-life index symptoms domain (sym). Both time maintained above 75% of baseline (T(i)MCS and T(i)sym) and mean improvement (microMCS and microsym) were measured.

FINDINGS

NIV improved T(i)MCS, T(i)sym, microMCS, microsym, and survival in all patients and in the subgroup with better bulbar function (n=20). This subgroup showed improvement in several measures of quality of life and a median survival benefit of 205 days (p=0.006) with maintained quality of life for most of this period. NIV improved some quality-of-life indices in those with poor bulbar function, including microsym (p=0.018), but conferred no survival benefit.

INTERPRETATION

In patients with amyotrophic lateral sclerosis without severe bulbar dysfunction, NIV improves survival with maintenance of, and improvement in, quality of life. The survival benefit from NIV in this group is much greater than that from currently available neuroprotective therapy. In patients with severe bulbar impairment, NIV improves sleep-related symptoms, but is unlikely to confer a large survival advantage.

Clinical Trials in ALS: What Did We Learn from Recent Trials in Humans?

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease. No treatment is currently able to stop the disease process. In the absence of new active compounds there is an urgent need to develop new strategies based on the neuroprotective activity of available drugs. ALS is a heterogeneous disease. To build up these therapeutic trials, we need to have a better understanding of the prognostic factors in this disease. During the Phase IV Rilutek Trial in France, we developed in a large population of patients a prognostic score based on clinical parameters available at the bedside. The most significant variables are vital capacity, spasticity, fasciculations, swallowing, cough and creatininemia. This score proved to be very useful in daily use in the clinic and for planning disease management in ALS as in the design of therapeutic trials. In ALS clinical trials, efficacy can be evaluated using survival or functional parameters. In phase II trials, function remains the most commonly used. In phase III trials, the gold standard endpoint remains the survival rate at month 18. We analyzed the most recent ALS trials published in the literature. This review suggests that in these trials there is a discrepancy between drug effects on survival versus function. These results suggest that a reappraisal of strategies to identify therapeutic targets for ALS is required.

Surveillance et traitement des troubles respiratoires associés à la sclérose latérale amyotrophique

INTRODUCTION

In amyotrophic lateral sclerosis (ALS), respiratory muscle involvement is highly predictive of survival and quality of life (QOL). There is compelling evidence that non invasive ventilation (NIV) prolongs survival by several months and improves QOL more than any other currently available treatment. Frequent testing of pulmonary function and regular evaluations are recommended since 1999 by the American Academy of Neurology in order to take appropriate treatment decisions.

STATE OF ART

There are numerous tests available to evaluate respiratory status in ALS and it is important to know their sensitivity and specificity to recognize clinical risk situations. Some recent data suggest that sniff nasal pressure and maximal inspiratory pressure (MIP) can be performed reliably by most ALS patients and are more sensitive to decrements in inspiratory muscle strength than spirometry or arterial blood gasometry.

PERSPECTIVES

Airway obstruction caused by ineffective coughing is the principal cause of intolerance to NIV. Several factors other than respiratory muscle strength may affect pulmonary function: postural changes, nutritional status, infectious disease, drugs.

CONCLUSION

The neurologist has to coordinate multidisciplinary care, with attention to individual patient preferences, and with a frank and compassionate discussion between the patient, the family, the physicians and the caregivers.

Measures and markers in amyotrophic lateral sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disorder characterized by loss of spinal and cortical motor neurons, leading to progressive weakness and ultimately, death. Clinically, there appears to be an anatomic focus at disease onset, from which the disease then spreads. Because the focus of initial symptoms and the subsequent direction of spread can vary from patient to patient, disease monitoring is difficult, especially in a clinical trial, in which outcome measures must be identical and able to capture progression of all types. Thus, the search for markers of disease progression is especially important in ALS. Many approaches have been taken, from voluntary strength assessment and functional rating scales to physiological and pathological sampling of affected portions of nervous system. No proposed marker has been demonstrated to meet the desired criteria of biological meaning, sensitivity to disease progression, clear relationship to overall prognosis and survival, and ease of measurement. However, progress is being made in all of these regards.

Motor unit number estimation: new techniques and new uses

MUNE is a unique neurophysiologic tool because it can quantitatively estimate the number of motor neurons innervating a muscle or group of muscles. All other neurophysiologic techniques are influenced by collateral reinnervation and provide only a qualitative estimate of motor unit loss. Further, the S-MUPs obtained with MUNE provide quantitative information about the whole motor unit. Other routine neurophysiologic techniques provide information restricted to a portion of the motor unit. These unique features of MUNE have been applied to neurogenic disorders to yield a better understanding of disease processes. Various modifications are being developed that will provide more data and ease of use. It is anticipated that the availability of MUNE on EMG machines will grow and it use will expand from a research tool to a routine neurophysiologic test.

Clinical and neurophysiological evaluation of progression in amyotrophic lateral sclerosis

There is a need for a sensitive neurophysiological measure of disease progression in following the course of patients with amyotrophic lateral sclerosis (ALS). We studied two groups of nine ALS patients, one with slow progression (Group A) and the other with rapid progression (Group B). We evaluated muscle strength scores using the Medical Research Council (MRC) scale in limb and trunk muscles, forced vital capacity (FVC), and ALS functional rating scale (ALS-FRS) scores. Maximal voluntary isometric contraction (MVIC) of the abductor digiti minimi muscle (ADM) was measured, using a digital device. We also measured M-wave amplitude and area in the ADM, and the distal motor latency and F-wave frequency in the ulnar nerve; from these data, the neurophysiological index (NI) was calculated, as described previously. In both groups, the NI was the most sensitive measure of change, with the smallest coefficient of variation. We conclude that the NI, which requires no special technology and no new clinical or technical skills to use, is sensitive to change, and therefore may be useful in clinical trials, as well as in a clinical setting.

Amyotrophic lateral sclerosis: progress and prospects for treatment

Fifteen years ago, a role for excitotoxic damage in the pathology of amyotrophic lateral sclerosis (ALS) was postulated. This stimulated the development of riluzole, the only available treatment for the disease. Since then, the identification of abnormal forms of superoxide dismutase as the genetic basis of certain familial forms of ALS has provided a huge impetus to the search for new effective treatments for this devastating disease. Transgenic mouse models have been developed expressing these aberrant mutants that develop a form of motor neurone disease the progress of which can be slowed by riluzole. Studies in these mice have provided evidence for a role for excitotoxic, apoptotic and oxidative processes in the development of pathology. The mice can be used for testing molecules targeting these processes as potential therapies, to allow the most promising to be evaluated in humans. Several such agents are currently in clinical trials. Many previous clinical trials in ALS were insufficiently powered to demonstrate any relevant effect on disease progression. This situation has been to some extent remedied in the more recent trials, which have recruited many hundreds of patients. However, with the exception of studies with riluzole, the results of these have been disappointing. In particular, a number of large trials with neurotrophic agents have revealed no evidence for efficacy. Nonetheless, the need for large multinational trials of long duration limits the number that can be carried out and makes important demands on investment. For this reason, surrogate markers that can be used for rapid screening in patients of potential treatments identified in the transgenic mice are urgently needed.

Disease progression in amyotrophic lateral sclerosis: predictors of survival

Predicting the rate of disease progression has become important as trials of new medical treatments for amyotrophic lateral sclerosis (ALS) are planned. Bulbar onset, early impairment of forced vital capacity, and older age have all been associated with shorter survival. We performed a retrospective study to compare survival factors with disease progression in a German ALS population. We analyzed disease progression in 155 patients at intervals of 4 months over a period of 3 years. To evaluate disease progression, the ALS functional rating scale (ALS-FRS), forced vital capacity (FVC%), and a Medical Research Council (MRC) compound score based on a nine-step modified MRC scale were used. We compared age (< 55 years vs. > or =55 years), different sites of disease onset (bulbar vs. limb), and gender to the rate of disease progression and performed survival analyses. No overall significant difference could be detected when analyzing these subgroups with regard to disease progression. By contrast, significantly longer survival was observed in the younger age group (56 months vs. 38 months, P < 0.0001) and in patients with limb-onset disease (51 months vs. 37 months, P = 0.0002). Using Cox analyses values we found that the declines of ALS-FRS, FVC%, and MRC compound score were predictive of survival (P < 0.0001, P = 0.002, and P = 0.003, respectively). Future studies are needed to clarify whether nonspecific factors including muscle atrophy, dysphagia, and coexisting diseases influence prediction of survival in ALS patients. A more precise set of predictors may help to better stratify patient subgroups for future treatment trials.

Cost effectiveness of treatments for amyotrophic lateral sclerosis: a review of the literature

Amyotrophic lateral sclerosis (ALS) is a difficult to diagnose, fatal, progressive degenerative disease with an average survival time of 2 to 5 years. Percutaneous endoscopic gastrotomy (PEG) and bi-level intermittent positive pressure (BIPAP) ventilation may be the major interventions leading to longer survival of patients with ALS. Riluzole has been shown to have modest effects on survival (as opposed to functional) gains and is currently the only drug approved for the treatment of ALS. There is conflicting evidence with regard to the ability of recombinant human insulin-like growth factor (rhIGF-I) to retard ALS progression. Mechanical ventilation (via a tracheostomy tube) is expensive, but is widely used in later stage patients with ALS in the US. A review of nine cost-effectiveness studies of riluzole and one of rhIGF-I found the following: drug costs and survival gains are the major drivers of cost effectiveness; survival gains are estimated from truncated databases with a high degree of uncertainty; more accurate stage-specific utility weights based on patients who agreed to treatment are needed; case incidence-based evaluations should be carried out; cost-effectiveness ratios are insensitive to discount rates; employment and caregiver issues or externalities have been widely ignored; threshold acceptance cost-effectiveness values are ill-defined and evaluations are not generalisable to other countries because of cost and treatment style differences. On account of the high degree of uncertainty pertaining to survival gains and the relatively high costs per life years or quality-adjusted life-years gained, and while acknowledging that not every therapy has to be cost effective (e.g. orphan drugs), it is still inconclusive as to whether or not riluzole or rhIGF-1 can be considered as cost-effective therapies for ALS.

Environmental risk factors for amyotrophic lateral sclerosis

In order to evaluate reported associations of environmental risk factors with amyotrophic lateral sclerosis (ALS), consideration is given first to robust clinical and epidemiologic observations. These are observations which have persisted in time, have been replicated consistently and likely reflect the reality of the disease. Sporadic, familial and Western Pacific ALS are considered. In contrast, other associations appear to have emerged due to chance, sometimes compounded by faulty study design, and have dissipated once greater attention was given to methodological rigor. Current data suggest that there are no robust environmental risk factors for sporadic ALS.